The purpose of the proposed work is to isolate and characterize the etiologic agents of scrapie and transmissible mink encephalopathy (TME); to study the pathogenesis of scrapie and TME in suitable hosts; and to study the etiological and epidemiological interrelationships between the animal and human (kuru and Creutzfeldt-Jakob disease) encephalopathies. BIBLIOGRAPHIC REFERENCES: Marsh, R.F.; Sipe, J.C.; Morse, S.S.; and Hanson, R.P. (1976). Transmissible mink encephalopathy: Reduced spongiform degeneration in aged mink of the Chediak-Higashi genotype. Lab. Invest. 34: 492. Semancik, J.S.; Marsh, R.F.; Geelen, J.L.M.C.; and Hanson, R.P. (1976). Properties of the scrapie agent-endomembrane complex from hamster brain. J. Virol. 18: 693.